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Engineering Tool · Water Treatment

Granular Media Filter Designer

Review normal and one-filter-out loading, multilayer media headloss, and backwash water requirements.

Municipal Drinking WaterStage 03 — Clarification & Filtration
Status
Available
PROJECT · OPTIONAL

Project metadata

Report context for exports; it does not change calculations.Edit detailsHide details

01 · USER INPUT

Design basis and inputs

Enter each layer's volume-equivalent spherical particle diameter and separate sphericity. If a supplier gives an already shape-corrected surface-volume diameter, divide it by sphericity before entry.

Sand
Sand
Engineering calculations run locally in this browser after assets load.

02 · CALCULATED RESULT

Results at a glance

Load or enter inputs, then calculate to create an authoritative result.

03 · REPORTING

Exports and verification

CSV contains input and output detail. PDF uses the current calculation and report metadata.

Verification suite

Calculation revision 4f9f386b

66 focused fixtures: independent filter-bank, backwash, and multilayer Ergun cases; selected headloss basis, optional expansion, finite-result boundaries, validation, and structured reporting. Tests are deterministic and run without network access.
01

Engineering Basis

Methodology

Calculates normal and one-filter-out loading, backwash flow/volume, and clean-bed multilayer Ergun headloss from entered media and water properties. Enter volume-equivalent spherical particle diameter and apply sphericity separately; Ergun output is a clean-bed screen.

Normal rate = plant design flow / total active filter area. One-filter-out rate uses (N−1) equal filter areas. Rates are reported in m/d and m/h.

Backwash flow = backwash rate × area per filter. Wash volume = flow × duration. Daily volume includes entered washes per filter per day.

Backwash-water fraction = gross daily backwash-water volume / entered plant design flow; it does not represent net recovery.

Clean-bed headloss uses the Ergun equation for each entered layer and sums the layer losses. Enter the volume-equivalent spherical particle diameter; sphericity is applied separately. Velocity converts m/h to m/s; pressure drop converts to head using entered density and standard gravitational acceleration.

A declared bed expansion is applied to layer depth for a geometric screen only. Leaving it blank omits that screen.

Scope / Limitations

  • Compare normal, N−1, or custom headloss basis with declared media properties, backwash rate and duration, and optional bed expansion.
  • Does not recommend media chemistry, predict terminal run time from turbidity, predict pathogen removal, or claim regulatory filter credit.
  • Ergun output is a clean-bed screening estimate. Volume-equivalent spherical diameter, porosity, sphericity, and water properties must be supplied explicitly; do not enter an already shape-corrected surface-volume diameter without converting it first.
  • Bed expansion is not predicted from wash hydraulics.
02

Engineering Path

Upstream Context

  • Selected upstream solids-control basis Confirm the feed-water and solids-control assumptions before applying the selected media or advanced-barrier screen.

Current Tool Decision

  • Granular Media Filter Designer Review normal and one-filter-out loading, multilayer media headloss, and backwash water requirements.

Downstream Engineering Step

03

Related Resources

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